Gasoline carburetors have been used extensively in internal combustion engines. Small engines and large engines have both been designed with carburetors to provide the fuel and air mixture needed to power the engine. In particular, the engine pulls in a fuel and air mixture from the carburetor where it is combusted, producing mechanical power. The carburetor, in turn, pulls in fuel and air in the correct ratio and mixes them. Small engines, in particular, benefit from the relative simplicity of the carburetor and the mechanical reliability of the carburetor over long periods of time.
Gasoline, as a fuel, however, has a number of drawbacks. For example, gasoline engines, especially small engines, may need to be primed and properly choked to allow the engine to start. Over priming of the engine can flood the engine. Once the engine has been flooded, the operator must generally wait for a period of time for the excess gasoline to evaporate from the combustion chamber before attempting to once again start the engine.
In addition, gasoline does not work well as a fuel at colder temperatures. In particular, in colder applications engines often will not start on their own. Instead the engine must be heated before starting or else the gasoline will not ignite. I.e., the operator must turn on a heater, either electric or using some other fuel source, which heats the engine for a time before turning on the engine. This can lead to unacceptable delays.
Further, gasoline produces a high amount of carbon dioxide emissions. Carbon dioxide is considered by some to be a greenhouse gas, the excess production of which is implicated in global warming. In addition, gasoline can contain a number of other pollutants, such as sulfur, carbon monoxide, nitrogen oxides and hydrocarbons, which can be released into the atmosphere when the gasoline is combusted. The production of these pollutants has become highly regulated by a number of governments because of their adverse environmental effects.
Moreover, gasoline makes for difficult throttle control. That is, slight changes in the throttling of gasoline engines can make for large changes in the power produced in the engine. Additionally, the ratio of gasoline to air is quite sensitive, making precise throttling adjustments with gasoline engines difficult. This is particularly true at lower temperatures. The ratio of gasoline to air needs to be higher at lower temperature and lower at higher at lower temperatures, making the engine difficult to control at times, especially in cold weather applications. This can be especially troublesome when precise engine control is required.
Finally, gasoline which is spilled can contaminate the immediate area. The gasoline can evaporate into the atmosphere where it is a pollutant. Alternatively, the gasoline can foul other equipment. For example, in ice fishing a drill is used to drill through the ice to reach water. If the ice fisherman spills gasoline or gets it on his hands or otherwise spreads it such that the gasoline gets on the fishing equipment, the equipment is fouled and cannot be used until the equipment is cleaned.
There are other fuels available for engines. For example, natural gas, propane and other volatile hydrocarbons are readily available. Because they are gases when not stored under pressure the chances of contamination are much lower. Additionally, engines using volatile hydrocarbons do not need to be primed, as the fuel naturally and quickly diffuses to the combustion chamber. Further, the operating temperature ranges of these fuels are much larger and the throttle control may be much better. However, standard carburetors are poorly suited for propane engines and engines which use other volatile hydrocarbons. The ratio of fuel to air in these engines can vary dramatically from the ratio used in a gasoline engine.
Accordingly, there is a need in the art for a carburetor which works with non-gasoline engines. Further, there is a need in the art for the carburetor to provide accurate throttle control for the engine, even at lower temperatures. In addition, there is a need in the art for a carburetor which works with fuels that are unlikely to contaminate other equipment.